Call button



FIG. 1 is a perspective view of a call button, showing the new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right-side elevational view thereof;

FIG. 5 is a left-side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines showing an instruction sign in FIG. 1 are included for the purpose of illustrating the invention in use, and form no part of the claimed design. 

What is claimed is the ornamental design for a call button, as shown and described. 